My point to Geek boy is that you can't criminally charge someone for ballot harvesting when it's legal to do so. The problem with ballot harvesting is that the ballot is uncontrolled, and authorities have ZERO means to know if it was legally filled out or not. The harvester could also destroy ballots harvested and never be caught. Those giving such a person their ballot would not know it was destroyed rather than counted.
Drop boxes, while not so virulent a means of fraud as ballot harvesting, have their own issues. When the two are coupled, the harvester remains anonymous and is able to drop off ballots with little or no responsibility for those ballots. That is, they can dump in a bunch of collected ballots and the authorities have no idea who they were and who's ballots they collected.
It's a recipe for mass fraud, especially when you couple it to an election "season" lasting weeks or even months.